Light source



J ly 3, 1968 H FLEISHMAN ETAL 3,393,967

LIGHT SOURCE Filed May 6, 1966 FIG.\ 22 FIGZ 2 i IO HERMAN FLEISHMAN 44 ROBERT EVANS NTORS ATTORNEY United States Patent Oflice 3,393,967 Patented July 23, 1968 3,393,967 LIGHT SOURCE Herman Fleishman, Mount Vernon, N.Y., and Robert Evans, Denver, Colo., assignors to Astrosystems International Inc., a corporation of New Jersey Filed May 6, 1966, Ser. No. 548,272 12 Claims. (Cl. 431-158) ABSTRACT OF THE DISCLOSURE A tubular combustion chamber of optically transparent fused quartz provides light through the heating to incandescence, in or on the chamber, of spectrally emissive matter in the visible region, or of the inside surface of the quartz chamber, or both. Burning gases are introduced into one end of the tubular chamber and exhausted from a tapered orifice at the other end.

This invention relates to a light source for illuminating a large area. The invention has particular relationship to a light source which may be attached to a helicopter or some other airborne vehicle for illuminating a large land area beneath the vehicle. Many types of lamps have been designed for high intensity use, the most successful of which is the electric arc lamp. While this source of illumination produces an intense point source of light which can be focused into a concentrated beam, the equipment necessary for maintaining the arc is quite expensive and very heavy. Many other types of intense light sources have been produced but they all use electrical power and require considerable auxiliary equipment. The light source described herein uses no electrical power except for ignition. Two containers of gas or fluid are all that is required to maintain the source for a considerable length of time. The auxiliary equipment is not heavy and the lamp itself is a small compact unit and does not include any evacuated chambers.

One of the objects of this invention is to provid an improved light source which avoids one or more of the disadvantages and limitations of prior art lamps.

Another object of the invention is to provide an intense source of light for illuminating a large area.

Another object of the invention is to generate luminous flux by the combination of a liquid or gas fuel and a gas oxidizer.

Another object of the invention is to reduce the cost and complexity of light generating units.

Another object of the invention is to provide a light generator which is rugged and has a long operating life.

Another object of the invention is to provide a light generating device whose light producing characteristics are not etfected by atmospheric conditions.

The light source includes a hollow cylindrical tube of fused quartz having a mixing chamber at one end and an exit orifice at the other end. A first conduit is connected to the mixing chamber for supplying a liquid fuel. A second conduit is also connected to the mixing chamber for supplying an oxidizing gas. An igniter means, such as a spark plug, is positioned at the mixing chamber for igniting the mixture of fuel and oxidizing gas and thereby provides a flame for heating the quartz tube to incandescence.

For a better understanding of the present invention, together with other and further objects thereof, reference is made to the following description taken in connection with the accompanying drawings.

0 FIG. 1 is a side view of the lamp housing mounted 7 below fuel and oxidizing tanks.

FIG. 2 is a cross sectional view of the arrangement shown in FIG. 1 and is taken along line 2-2 of that figure.

FIG. 3 is an alternate form of the invention showing a tank container and a control unit mounted exterior to the lamp which is connected to the control unit by a long supply cable.

FIG. 4 is a cross sectional view of a portion of the lamp unit showing the quartz tube with an auxiliary layer of light producing substance.

FIG. 5 is a cross sectional view showing the details of the combustion chamber, the mixing chamber, and the supporting fixtures.

Referring now to the drawings, FIG. 1 shows a large tank 10 which may hold the oxidizing gas such as oxygen. Mounted below tank 10 is a second tank 11 which holds a fuel, either gas or liquid. A third tank 12 may be mounted on the other side of the assembly and may hold other gases or fluids such as nitrogen for pressurizing the liquid fuel. The light source itself 13 is mounted directly below tank 10 and may be positioned between two reflectors 14 and 15. The reflectors help to intensify the light directed downwardly and they form a barrier which prevents the light source 13 from illuminating the airborne vehicle which is supporting the source. A lens 16 may be mounted below the reflectors, but this is not always necessary and may be omittcd.'Two or more supports 17 and 18 may be secured to tank 10 for supporting the arrangement on the ground prior to being airborne. One or more brackets 20 and 21 are secured to the tank 10 for support by cables 22 when the device is lowered from an airplane or helicopter during flight.

FIG. 3 shows the preferred arrangement whereby a light source 23 is provided with cables 22 with the three tanks 10. 11, and 12 housed within a compartment 24 having a control panel 25 for operation by an operator within the helicopter. The housing 24 is supported in th helicopter or other vehicle and is connected to the light source 23 by means of a cable 26, this cable including flexible conduits for transmission of the gases and an electric transmission line for providing the spark plug with electrical energy for igniting the gas mixture.

FIG. 4 shows the fused quartz cylinder with an added layer of material which gives added brightness to the intcrior surface of the cylinder. This additional layer 27 may be quite thin and the material added may be diffused into the quartz. One such material is calcium oxide which gives a brilliant white light when heated to a temperature in the range of 1,500 to 4,000 degrees centigrade. Many other metal oxides such as sodium oxide, cerium oxide and thorium oxide, are available for deposition on the inside surface of the quartz cylinder. Some of these oxides produce a color which is predominate in other spectral emmission regions. By using quartz cylinder with different layers. a large range of color combinations is possible. it should be noted that while the quartz alone sublimes under continual application of high temperature flames. other oxides such as calcium and cobalt are more stable and resist sublimation. Layer 27 is deposited on the inner surface of the inner tube 28.

Referring now to FIG. 5. the detailed construction of the lamp is shown. The inner quartz cylinder 28 is shown with a layer of added oxide material 27. Surrounding this tube 28 is an outer tube 30, also of fused quartz. which is designed to be a permanent transparent retaining tube. The inner tube 28, because of the high temperatures applied to it may sublime or otherwise disintegrate and for this reason may require renewal after a number of active hours of service.

The exit end of the quartz tubes is surrounded by a block of metal 31. An added liner 32 of tantalum tungsten alloy is mounted adjoining tube 28 and contains an orifice 33 which permits the burned compounds to escape into the atmosphere. The copcnrling application of common assignee herewith, Ser. No. 680,397, filed Nov. 3, 1967, entitled Enhanced Output Light Source," by John C. Holme, discloses and claims, inter alia, certain features of an escape orifice such as orifice 33. which are not here claimed and are no part of the instant invention. At the other end of the tube 28 a biock 41 includes a mixing chamber 34 where the fuel and the oxidizer gases are mixed and then discharged into the interior of tube 23. The mixing chamber 34 is connected by a first conduit 35 to a tank containing fuel fluid. A solenoid valve 36 is mounted in series with conduit 35 so as to open or close the supply line to the mixing chamber. In a similar manner, conduit 37 supplies the oxidizing gas to the mixing chamber in series with a solenoid operated fuel valve 38.

The input terminal and the output terminal are mounted on either ends of the combustion tube 28 and may be clamped together by any suitable means such as bolts 40. The mixing chamber and the valves 36. 38 are all mountcd in a recess in terminal block 41. An expandable washer 44 of heat insulation is placed between the ends of the quartz cylinders and block 41.

The operation of this type of light source is as follows: after being lowered from a helicopter, the valves 36 and 38 are opened by remote control and a mixture of inflam mable gas is delivered to the combustion chamber defined by the inner-surface 27. At this point current is applied to the high tension coil 42 and the spark electrode 43 and a spark jumps across the gap to ignite the combustible mixture in chamber 34. This flame raises the temperature of the inside surface of tube 28 and causes the quartz cylinder to light up. If an inner layer 27 is used it also becomes incandescent. After heating the inner surface 27 to incandescence, the burned gases are ejected through the exit port 33. This action provides a brilliant white light which may be applied to any large land area. When used alone without any storage tanks. the light source may be suspended by one or more cables 45.

From the above description and drawings it will be evident that a simplified light source has been provided. In order to produce an incandescent temperature for lighting up the quartz or the added layer, the quartz may be come soft and may be slightly deformed. The outer cylinder 30 is designed to supplement the inner cylinder and to act as a cooling member.

The foregoing disclosure and drawings are merely illus trative of the principles of this invention and are not to be interpreted in a limiting sense. The only limitations are to be determined from the scope of the appended claims.

We claim:

1. A light source comprising, a hollow cylindrical tube of fused quartz, a mixing chamber secured to one end of the tube for producing a combustible gas mixture, 21 first conduit connected to the mixing chamber for supplying fuel, a second conduit connected to the mixing chamber for supplying an oxidizing agent, an igniter means positioned to an output orifice of said mixing chamber for igniting the mixture of fuel and oxidizing agent, an exit orifice at the other end of the cylindrical tube for the elimination of the burnt gases, and a layer of a metallic oxide deposited on the inner surface of said cylindrical tube for increasing the spectral emissivity.

2. A light source as claimed in claim 1 wherein said layer is a substance selected from the group consisting of calcium oxide, thorium oxide, cerium oxide and sodium oxide.

3. A light source as claimed in claim 1 wherein said exit orifice is composed of an alloy of tantalum and tungsten.

4. A light source as claimed in claim 1 wherein said first and second conduits are each connected through remote controlled valves.

5. A light source as claimed in claim 1 wherein a second hollow fused quartz cylindrical tube is fitted over said tube for mechanical stability.

6. A light source as claimed in claim 5 wherein said quartz cylinders are clamped between two metal end pieces, one of which contains the mixing chamber and the other of which surrounds the exit orifice.

7. A light source, comprising: A combustion chamber of optically transparent refractory material; means for introducing and sustaining burning gases in an input region of said chamber; exhaust means at an exhaust region of said chamber for exhausting said burning gases; and matter which provides a greater magnitude of spectral emissivity in the visible region than in the invisible region when heated to temperatures provided by said sustained burning gases, said emissive matter located in the path of heat radiated by said gases and contiguous with a wall of said combustion chamber.

8. A light source as recited in claim 7 wherein said matter is deposited as a layer on the inner surface of said combustion chamber.

9. A light source as recited in claim 7 wherein said matter is diffused in the Wall of said combustion chamber.

10. A tight source as recited in claim 7 wherein said spectraliy emissive matter is a metallic oxide.

11. A light source as recited in claim 7 wherein said combustion chamber is a tubular vessel of fused quartz.

12. A light source as recited in claim 7 wherein said spectrally emissive matter is a discrete emitter in the visible region of the spectrum.

References Cited UNITED STATES PATENTS 1,689,551 10/1928 Hammond. 1,415,063 5/1922 Smith 6787 FOREIGN PATENTS 9,223 4/1912 Great Britain. 39,771 12/1915 Sweden.

JAMES W. WESTHAVER, Primary Examiner. 

